Artificial dialysis for patients with end-stage renal failure is broadly divided into hemodialysis and peritoneal dialysis. Among these, the peritoneal dialysis is a method in which a hypertonic dialysis fluid containing glucose or a polysaccharide thereof as an osmotic agent is injected into the peritoneal cavity and excess waste products, water, and electrolytes in the body are removed with the use of the function of the peritoneum as a semipermeable membrane. The peritoneal dialysis has many advantages as compared with the hemodialysis in that the need for dietary or activity restriction is lower, the effect on hemodynamics is lower, preservation of residual renal function is better, rehabilitation is easier, etc. However, in recent years, various disorders due to prolonged peritoneal dialysis, for example, poor water removal or insufficient removal of waste products accompanying deterioration of peritoneal function has become a serious problem. The deterioration of peritoneal function is deeply associated with an advanced glycation end product (AGE) generated by a reaction between glucose contained in a peritoneal dialysis fluid as an osmotic agent and a protein, a reactive oxygen species (ROS) produced by binding of AGE to a cell having a receptor thereof or exposure of the cell to high concentration of glucose.
In order to solve the problems as described above, a search for a substance that inhibits deterioration of peritoneal function caused by glucose or a polysaccharide thereof and a search for a novel osmotic agent alternative to glucose or a polysaccharide thereof have been performed, and a chondroitin sulfate (CS) which is a sulfated glycosaminoglycan has already been proposed as a candidate substance (For example, Patent Document 1 and Non-patent Document 1).    Patent Document 1: JP-A-1-151462    Non-patent Document 1: Ohno T., Imada A., “The usefulness of sodium chondroitin sulfate as an osmotic agent for peritoneal dialysis”, Toseki kaishi (The Journal of the Japanese Society for Dialysis Therapy), 30(1): 65, 1997